Active damper for a planetary gear arrangement

Abstract

A planetary gear arrangement having at least three rotatable members with intermeshing gears and a primary torque path defined therein. At least one active friction damper is disposed between two of the planetary gear members, for example, a sun gear and a ring gear. The active damper is selectively operable to apply frictional engagement between the two members with which it is interconnected to establish a controlled secondary torque path therebetween. The active damper is effective to reduce gear lash changes between the gear members of a planetary assembly.

1. A planetary gear arrangement comprising:
 three rotatable members, a first of which is a planet carrier assembly member having at least a planet carrier member and a plurality of pinion gear members rotatably mounted on said planet carrier member, a second of said rotatable members being disposed in meshing engagement with at least one of said pinion gear members, a third of said rotatable members being disposed in meshing engagement with at least one of said pinion gear members; 
 a selectively engageable active friction damper means comprised of a normally disengaged torque transmitting mechanism disposed between and adapted to selectively apply a frictional engagement between at least two of said rotatable members within an individual planetary gear arrangement during a torque reversal through said planetary gear arrangement; 
 means for selectively activating said active friction damper for engagment in anticipation of a lash change between said rotatable members to minimize lash within said individual planetary gear arrangement prior to a torque reversal associated with a gear change event or other transient driveline disturbance to provide frictional damping and minimize noise. 
 
     
     
       2. The planetary gear arrangement defined in  claim 1  further wherein:
 said two members engaged by said active damper means are a sun gear member and a ring gear member. 
 
     
     
       3. The planetary gear arrangement defined in  claim 1  further wherein:
 said two members engaged by said active damper means are a ring gear member and said planet carrier member. 
 
     
     
       4. The planetary gear arrangement defined in  claim 1  further wherein:
 said two members engaged by said active damper means are a sun gear member and said planet carrier member.